From 60f62d3e4baaef13fa277b9439a33611488b532a Mon Sep 17 00:00:00 2001
From: Tomi Jaga <jagatomi12@gmail.com>
Date: Sat, 30 Dec 2023 19:29:42 -0500
Subject: [PATCH] [Fix]: fix the redundant addition of the self-describe tag to
 each nested value

---
 src/CBOR/lib.mo    | 28 +++++++++++++---------------
 tests/CBOR.Test.mo | 22 ++++++++++++++++++++++
 2 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/src/CBOR/lib.mo b/src/CBOR/lib.mo
index e036db0..023e7d0 100644
--- a/src/CBOR/lib.mo
+++ b/src/CBOR/lib.mo
@@ -24,8 +24,10 @@ module {
     type Result<A, B> = Result.Result<A, B>;
     type CBOR = CBOR_Value.Value;
 
+    public type Options = CandidTypes.Options;
+    
     /// Converts serialized Candid blob to CBOR blob
-    public func encode(blob : Blob, keys : [Text], options: ?CandidTypes.Options) : Result<Blob, Text> {
+    public func encode(blob : Blob, keys : [Text], options: ?Options) : Result<Blob, Text> {
         let decoded_res = Candid.decode(blob, keys, options);
         let #ok(candid) = decoded_res else return Utils.send_error(decoded_res);
 
@@ -39,7 +41,9 @@ module {
         let res = transpile_candid_to_cbor(candid);
         let #ok(transpiled_cbor) = res else return Utils.send_error(res);
 
-        switch(CBOR_Encoder.encode(transpiled_cbor)){
+        let cbor_with_self_describe_tag = #majorType6({ tag = 55799 : Nat64; value = transpiled_cbor; });
+
+        switch(CBOR_Encoder.encode(cbor_with_self_describe_tag)){
             case(#ok(encoded_cbor)){ #ok (Blob.fromArray(encoded_cbor))};
             case(#err(#invalidValue(errMsg))){ #err("Invalid value error while encoding CBOR: " # errMsg) };
         };
@@ -109,13 +113,10 @@ module {
             };
         };
 
-        // add self-describe tag
-        let tagged_cbor = #majorType6({ tag = 55799 : Nat64; value = transpiled_cbor; });
-
-        #ok(tagged_cbor);
+        #ok(transpiled_cbor);
     };
 
-    public func decode(blob: Blob, options: ?CandidTypes.Options): Result<Blob, Text> {
+    public func decode(blob: Blob, options: ?Options): Result<Blob, Text> {
         let candid_res = toCandid(blob);
         let #ok(candid) = candid_res else return Utils.send_error(candid_res);
         Candid.encodeOne(candid, options);
@@ -125,7 +126,10 @@ module {
         let cbor_res = CBOR_Decoder.decode(blob);
         
         let candid_res = switch (cbor_res) {
-            case (#ok(cbor)) transpile_cbor_to_candid(cbor);
+            case (#ok(cbor)) {
+                let #majorType6({ tag = 55799; value }) = cbor else return transpile_cbor_to_candid(cbor);
+                transpile_cbor_to_candid(value);
+            };
             case (#err(cbor_error)) {
                 switch(cbor_error){
                     case (#unexpectedBreak){ return #err("Error decoding CBOR: Unexpected break") };
@@ -176,13 +180,7 @@ module {
                 return #err("Error decoding CBOR: #_break is not supported");
             };
             case (#majorType6(tagged_cbor)) {
-                if (tagged_cbor.tag == 55799){
-                    let transpiled_candid_res = transpile_cbor_to_candid(tagged_cbor.value);
-                    let #ok(transpiled_candid) = transpiled_candid_res else return Utils.send_error(transpiled_candid_res);
-                    transpiled_candid
-                } else {
-                    return #err("Error decoding CBOR: Tagged values are not supported");
-                };
+                return #err("Error decoding CBOR: Tagged values are not supported");
             };
         };
 
diff --git a/tests/CBOR.Test.mo b/tests/CBOR.Test.mo
index 3fd0305..6bc2fbc 100644
--- a/tests/CBOR.Test.mo
+++ b/tests/CBOR.Test.mo
@@ -1,4 +1,6 @@
 // @testmode wasi
+import Array "mo:base/Array";
+import Blob "mo:base/Blob";
 import Debug "mo:base/Debug";
 import Iter "mo:base/Iter";
 import { test; suite } "mo:test";
@@ -45,6 +47,7 @@ suite(
             assert opt_text2 == opt_text;
 
         });
+
         test(
             "primitives",
             func() {
@@ -82,6 +85,23 @@ suite(
                 let #ok(list_cbor) = CBOR.encode(list_candid, [], null);
                 let #ok(record_cbor) = CBOR.encode(record_candid, ["a", "b"], null);
 
+                let self_describe_tag : Blob = "\D9\D9\F7";
+
+                func blob_concat(b1: Blob, b2: Blob): Blob = Blob.fromArray(Array.append(Blob.toArray(b1), Blob.toArray(b2)));
+                func sdt(blob: Blob): Blob = blob_concat(self_describe_tag, blob);
+
+                // cbor encodings from https://cbor.me/
+                assert nat_cbor == sdt("\18\7B");
+                assert int_cbor == sdt("\38\7A");
+                assert float_cbor == sdt("\FB\40\5E\DD\2F\1A\9F\BE\77");
+                assert bool_cbor == sdt("\F5");
+                assert text_cbor == sdt("\65\68\65\6C\6C\6F");
+                assert blob_cbor == sdt("\43\01\02\03");
+                assert null_cbor == sdt("\F6");
+                // assert empty_cbor == sdt("\F7"); // mapped to undefined
+                assert list_cbor == sdt("\83\01\02\03");
+                assert record_cbor == sdt("\A2\61\61\01\61\62\02");
+
                 let #ok(nat_candid2) = CBOR.decode(nat_cbor, null);
                 let #ok(int_candid2) = CBOR.decode(int_cbor, null);
                 let #ok(float_candid2) = CBOR.decode(float_cbor, null);
@@ -106,5 +126,7 @@ suite(
 
             },
         );
+
+        
     },
 );